Long-term efficient composition for active layer and organic solar cell including the same

Abstract

Disclosed herein are an at least quaternary composition that comprises at least two donor components and at least two low-molecular-weight fullerene acceptor components and is able to allow for superior photovoltaic performance over a long period of time, and an organic solve cell comprising an active layer formed thereof.

The invention claimed is: 
     
       1. An at least quaternary composition for use in an active layer of an organic photovoltaic, the composition comprising:
 (I) a donor component including a first donor component and a second donor component that absorb light to create an exciton and donate the electron separated from the exciton formed; and (II) an acceptor component including a first low-molecular-weight fullerene acceptor component and a second low-molecular-weight fullerene acceptor component that receive the electron donated by the donor component, 
 wherein, the first donor component is a material having a bandgap of 1.1 to 2.5 eV, 
 the second donor component is a material having a LUMO (lowest unoccupied molecular orbital) identical to or lower than a LUMO of the first donor component, 
 the first low-molecular-weight fullerene acceptor component has a cascade energy level structure with the second donor component and the second donor component has a HOMO (highest occupied molecular orbital) identical to or higher than a HOMO of the first low-molecular-weight fullerene acceptor component, and 
 the second low-molecular-weight fullerene acceptor component has a cascade energy level structure with the first low-molecular-weight fullerene acceptor component and a LUMO higher than the HOMO of the first low-molecular-weight fullerene acceptor component. 
 
     
     
       2. The at least quaternary composition of  claim 1 , wherein the donor component (I) and the acceptor component (II) are contained at a mass ratio of 1:1 to 1:3 in the at least quaternary composition, the content of the first donor component in the donor component (I) ranges from 1 to 99% by mass, and the content of the first low-molecular-weight fullerene acceptor component in the acceptor component (II) ranges from 1 to 99% by mass. 
     
     
       3. The at least quaternary composition of  claim 1 , further comprising chlorobenzene, chloroform, para-xylene, dichlorobenzene, trichlorobenzen, hexane, THF, or a combination thereof as an organic solvent for forming a layer in an organic photovoltaic. 
     
     
       4. The at least quaternary composition of  claim 3 , wherein the organic solvent is contained in an amount of 1 to 4% by mass on the basis of the total mass of the at least quaternary donor and acceptor components. 
     
     
       5. The at least quaternary composition of  claim 1 , wherein the LUMO of the second donor component is lower by up to 50% than that of the first donor component and higher by at least 0.3 eV than that of the first low-molecular-weight fullerene acceptor component. 
     
     
       6. The at least quaternary composition of  claim 1 , wherein the HOMO of the second donor component is higher by at least 0.3 eV than that of the first low-molecular-weight fullerene acceptor component. 
     
     
       7. The at least quaternary composition of  claim 1 , wherein the second low-molecular-weight fullerene acceptor component has the LUMO lower than that of the first donor component. 
     
     
       8. The at least quaternary composition of  claim 1 , wherein the LUMO of the second low-molecular-weight fullerene acceptor component is higher by up to 50% than the HOMO of the first low-molecular-weight fullerene acceptor component and lower by at least 0.3 eV than the LUMO of the first donor component. 
     
     
       9. The at least quaternary composition of  claim 1 , wherein a HOMO of the second low-molecular-weight fullerene acceptor component is lower than a LUMO of the first low-molecular-weight fullerene acceptor component. 
     
     
       10. The at least quaternary composition of  claim 1 , wherein a HOMO of the second low-molecular-weight fullerene acceptor component is lower by up to 50% than a LUMO of the first low-molecular-weight fullerene acceptor component. 
     
     
       11. The at least quaternary composition of  claim 1 , wherein the first donor component and the second donor component range in bandgap from 1.1 to 2.5 eV and from 1.2 to 2.6 eV, respectively. 
     
     
       12. The at least quaternary composition of  claim 1 , wherein the first low-molecular-weight fullerene acceptor component and the second low-molecular-weight fullerene acceptor component range each in bandgap from 1.5 to 2.5 eV. 
     
     
       13. The at least quaternary composition of  claim 1 , wherein the first donor component is poly[[4,8-bis[(2-ethylhexyl)oxy]benzo[1,2-b:4,5-b′]dithiophene-2,6-diyl][3-fluoro-2-[(2-ethylhexyl)carbonyl]thieno[3,4-b]thiophenediyl]]; PTB7). 
     
     
       14. The at least quaternary composition of  claim 1 , wherein the first donor component is a polymer material comprising the repeating unit represented by one of the following General Formulas 2 to 5 or a combination thereof: 
       
         
           
           
               
               
           
         
       
     
     
       15. The at least quaternary composition of  claim 1 , wherein the first donor component is a polymer having a molecular weight (Mw) of 10,000 to 500,000. 
     
     
       16. The at least quaternary composition of  claim 1 , wherein the second donor component is PCDTBT, F8TBT, PPV, MDMO-PPV, MEH-PPV, P3HT, PBDTTT-CF, F8BT, PSBTBT, PBTTPD, TQ1, or a combination thereof and has a molecular weight (Mw) of 10,000 to 500,000. 
     
     
       17. The at least quaternary composition of  claim 1 , wherein the first low-molecular-weight fullerene acceptor component is C60, C70, C84, PC 71 BM, PC 61 BM, ICBA, ICMA, [6,6]-Thienyl C61 butyric acid methyl ester, or a combination thereof. 
     
     
       18. The at least quaternary composition of  claim 1 , wherein the second low-molecular-weight fullerene acceptor component is C60, C70, C84, PC 71 BM, PC 61 BM, ICBA, ICMA, [6,6]-Thienyl C61 butyric acid methyl ester, or a combination thereof. 
     
     
       19. The at least quaternary composition of  claim 1 , having a pristine hole mobility (μ h )/electron mobility (μ c ) ratio of 0.8 to 2. 
     
     
       20. An organic photovoltaic, comprising:
 a pair of electrodes including a cathode and an anode different in work function from each other; and 
 an active layer disposed between the pair of electrodes, wherein the active layer comprises the at least quaternary composition according to one of  claim 1 .